A. Coello

Oocyte vitrification as an efficient option for elective fertility preservation

OBJECTIVE To provide a detailed description of the current oocyte vitrification status as a means of elective fertility preservation (EFP). DESIGN Retrospective observational multicenter study. SETTING Private university-affiliated center. PATIENT(S) A total of 1,468 women who underwent EFP because of age or having associated a medical condition other than cancer (January 2007 to April 2015). INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Survival and cumulative live birth rate (CLBR) per consumed oocyte. RESULT(S) Mean age was higher with EFP due to age versus having an associated medical reason (37.7 y [95% confidence interval (CI) 36.5-37.9] vs. 35.7 y [95% CI 34.9-36.3]). In total, 137 patients (9.3%) returned to use their oocytes. Overall survival rate was 85.2% (95% CI 83.2-87.2). Live birth rate per patient was higher in women ≤35 years old than ≥36 years old (50% [95% CI 32.7-67.3] vs. 22.9% [95% CI 14.9-30.9]). CLBR was higher and increased faster in younger women. The gain in CLBR was sharp from 5 (15.4%, 95% CI -4.2 to 35.0) to 8 oocytes (40.8%, 95% CI 13.2-68.4), with an 8.4% gain per additional oocyte, in the ≤35-year-old group. The increase was slower with 10-15 oocytes, reaching a plateau CLBR of 85.2%. A milder increase (4.9% gain) was observed in the ≥36-year-old group (from 5.1% [95% CI -0.6 to 10.7] to 19.9% [95% CI 8.7-31.1] when 5-8 oocytes were consumed), reaching the plateau with 11 oocytes (CLBR 35.6%). Forty babies were born. CONCLUSION(S) At least 8-10 metaphase II oocytes are necessary to achieve reasonable success. Numbers should be individualized in women >36 years old. We suggest encouraging women who are motivated exclusively by a desire to postpone childbearing because of age, to come at younger ages to increase success possibilities.

Analysis of the morphological dynamics of blastocysts after vitrification/warming: defining new predictive variables of implantation

OBJECTIVE To describe the morphological dynamics of vitrified/warmed blastocysts and to identify quantitative morphological variables related to implantation. Subsequently, by using the most predictive parameters, to develop a hierarchical model by subdividing vitrified/warmed blastocysts into categories with different implantation potentials. DESIGN Observational, retrospective, cohort study. SETTING University-affiliated private IVF center. PATIENT(S) The study included 429 vitrified/warmed blastocysts with known implantation data, which were evaluated by time-lapse imaging. Blastocysts were routinely placed in EmbryoScope (Vitrolife) immediately after warming until transfer. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Embryos were vitrified and warmed by the Cryotop method (KitazatoBiopharma). The studied variables included the initial and minimum thicknesses of zona pellucida (μm), the initial and maximum areas (μm2), the area of inner cell mass (μm2), expansion (whether the embryo reexpands or not after warming), and collapsing or contraction after warming. After defining the optimal ranges according to the consecutive quartiles with the highest probability of implantation, a logistic regression analysis was performed by combining the former variables and the blastocyst morphological classification criteria defined by the Spanish Association of Embryologists into A, B, C, or D categories. RESULT(S) Reexpansion of vitrified/warmed blastocysts correlated strongly with implantation (44.6% for reexpanded vs. 6.5% for the blastocysts that did not reexpand after warming). Throughout the logistic regression analysis, the model identified the maximum blastocyst area, odds ratio (OR) = 0.41 (95% confidence interval [CI], 0.22-0.77), followed by the initial area, OR = 0.62 (95% CI, 0.35-1.08) as the most predictive variables related to implanting embryos. Blastocyst morphology was not considered relevant in our model. The hierarchical tree model subdivided embryos into four categories, A-D, with lowering expected implantation potentials (from 47.3% for A to 14.2% for D). CONCLUSION(S) The analysis of warmed blastocysts by time-lapse imaging may provide objective quantitative markers for the blastocyst implantation potential. We propose a hierarchical model to classify vitrified/warmed blastocysts according to their implantation probability. The observed correlations and the proposed algorithm should be validated in a prospective trial to evaluate its efficacy.

Oocyte dysmorphisms are not associated with post warming survival, fertilization and embryo development in own oocytes vitrification cycles

Materials and Methods: The study included a total of 416 MII oocytes obtained from 88 patients. Morphology evaluation was assessed before vitrification under 400x magnification. A total of 147 dysmorphic oocytes were detected. Oocyte dismorphisms included diffuse cytoplasmic granularity, centrally located cytoplasmic granular area, smooth endoplasmic reticulum, vacuoles, shape abnormalities, large perivitelline space and abnormal zona pellucida. Oocytes were vitrified and warmed with Cryotop method (KitazatoBiopharma). Chi-square test was performed to compare proportions among groups. P< 0.05 was considered statistically significant.